Gear mounting



get. 12, 1948. H J, KENT 2,451,342

GEAR MOUNHNG Filed June 7, 1947 V EN TOR.

Patented Oct. 12, 1948 GEAR MOUNTING Henry J. Kent, Teaneck, N. J., assignor to Kearfott Company, Inc., New York, N. Y., a corporation of New York Application June 7, 1947, Serial No. {753,334

6 Claims.

This invention relates to mechanism for mounting a gear on a shaft and more particularly to a gear mounting for use on shafts of small motors or synchros which are required to operate with extreme accuracy.

An object of the invention is to provide a gear mounting of the above type which eliminates eccentricity and back-lash in parts which are made with commercial tolerances.

Another object is to provide a mounting of the above type in which the gear may be readily attached to or removed from the shaft.

Another object is to provide a mounting of the above type which does not greatly increase the cost of manufacture and which simplifies the assembly of the gear on the shaft.

Various other objects and advantages will be apparent as the nature of the invention is more fully disclosed.

In mounting small gears on the shafts of small motors or synchros such as those used in electrical follow-up systems, it has been customary to make the gear to fit the shaft as accurately as commercial tolerances permit and to secure the same to the shaft by a key and keyway. It has been found, however, that in such assemblies a certain amount of back-lash may be present. This back-lash may not be appreciable in the case of large gears and shafts, but is unacceptable in cases of the type above referred to where extreme accuracy is required. It has also been proposed to provide a gear with a split hub which is clamped about the shaft. This construction, however, has been found to produce a certain amount of eccentricity. Hence this type of securing means is likewise unacceptable where extreme accuracy is required.

In accordance with the present invention these I difficulties are overcome by providing a splined shaft on which the gear is accurately journalled for concentricity. A driving disk having a split projecting hub is mounted on the splined shaft and is provided with keys or teeth which enter the splines for securing the disk for rotation with the shaft. The hub is provided with a tapered end surface which engages a conical inner surface of a cooperating element for compressing the split hub and clamping the same securely to the shaft. The disk is then pinned to the gear and provides a positive drive in which all back-lash has been effectively eliminated. Inasmuch as the gear is journalled on the shaft independently of the driving disk the concentrioity of the gear is not affected by the clamping of the split hub of the 2 disk to the shaft. Hence both eccentricity and back-lash are eliminated.

Although the novel features which are characteristic of this invention are pointed out'more particularly in the claims,-the nature of the invention will be better understood by re'ferringto the following description, taken in connection with the accompanying drawing in which a specific embodiment thereof has been set forth for purposes of illustration.

In the drawing:

Fig. 1 is a partial section through a motor, on an enlarged scale, showing a gear mounting embodying the present invention; a

Fig. 2 is a partial sectional view through a portion of the gear, the drivingdisk and the clamping ring on a larger scale;

Fig. 3 is a front elevation 'of the driving disk; Fig. 4 is a front elevation of the clamping ring; and

Fig. 5 is a detail view,- partly in section, of the end of the shaft to which the gear is to be applied.

In the following description specific terms are used for convenience in referring to various details of the invention. It is to be understood, however, that these terms are tobe interpreted as broadly as the state of the art will permit.

Referring to the drawings more in detail, the invention is shown as applied to a motor 19 having a shaft I2. The motor includes a rotor; IA of mag: netic material carried by the shaft !2, a stator i5, and an end plate it carrying a bearing I in which the shaft [2 is journalled. The shaft I2 is shown as having a shoulder l8 bearing against the inner surface of the bearing l l for positioning purposes. The motor is of standard construction and only as much thereof has been shown as is necessary to an understanding of the present in vention. H

The shaft 12 is provided with. a plurality of axially extendingsplines or'grooves 2!! which extend from the position of the bearing I! to the end of the shaft. At the end the shaft is provided with threads 2! which are formed over the splines 20.

In accordance with the present invention a gear 25 is accurately fitted on a sleeve 26 which in turn is accurately journalled on the shaft 12 to obtain concentricity between the gear 25 and the shaft l2. A driving disk 30 is provided with a projecting split hub 3| having teeth 32 which enter the Various splines 29 on the shaft I2. The hub 3| is provided with a tapered end surface 33 which is adapted to engage the conical inner surface 34 of the clamping ring 35, bearing against 3 shims 36 seated against the outer surface of the bearing IT. The disk 30 is provided with a radial slot 38 through which a pin 39 extends. The pin 39 is rigidly secured to the gear 25 and fits the slot 38 accurately to eliminate any back-lash. A lock nut 40 is threaded onto the thread 2| and clamps the gear 25, disk 30, ring 35 and bearing I1 against the shoulder t8 of the shaft i2. lock nut' 40' is adjusted to cause the conical surface 34 of the ring 35 to clamp the split hub 3| of the disk 30 rigidly to the shaft l2.

For assembling the gear 25' on the shaft I Zitis" only necessary to first position the ring 35 against The The ring 35 may seat against a shoulder or stop on the.

the bearing [1, providing shims 3.6 if necessary to suitably position the ring 35. The disk is then positioned on the shaft l2 andthe gear 253 and sleeve 26 are located; against the disk 30 with the: pin. 3% extending; through theslot 38. of the disk 30. The lock nut 411' is theirv applied. over'the threads. 2 land istightened for clamping: pur- DflSes.

It will be: notedthat' the axial thrust produced by the-nut. 40- causesthe ring to: clamp the split hub 3| of thedisle 30- secu-relyto the shaft [2. Thehub. 34 is tightened. inthis manner to a point at. which. no back-lash. occurs; The con.- centricity of the disk 30! is unimportant. inasmuch as the slot 38 provides the necessary'clearance for the pin 33:. The pin-.3915: machined: to fit accurately Within. the slot 38 so-that me back.- lash occurs at that point.

It.v will. be. noted. that the; above con'structionz is simple: and. that; the parts: may be readily assembled or dismantled. It is particularly adapted tor use connection with small: shafts and gears wheneextreme. accuracy is required. A motorhas been shown for illustration only. The shaft l2.

may be connected. toa synchro or other rotary device.

Althoughaspecificembodimenthastbeen.shown for purposes. of illustration, it is-to-be understood that-the-im ention is only tobe limitedin accord.- ance with the scope. of the following claims.

Whatis claimed is:

l. A. gear assembly comprising a rotatableshaft having; a seriesof. axially extending splines formed therein. a gear journalledonsaid shaft, adriving disk. for said gear having a.- projecting. split. hub formed. with teeth registering with said splines, clamping means contracting the split hub to secure-the same rigidlytwsaid. shaft, and a member connecting, said. diskitdsaid. ge an. I

2.. Aigear; assemblycomprising a rotatable shaft having a: series: of. axially extending splines,

4 hub to secure the same rigidly to-said shaft, a radial slot in said disk and a pin carried by said gear and seating in said slot for driving said gear.

3. A gear assembly comprising a rotatable shaft having a series of axially extending splines formed therein, a gear journalled on said shaft, a driving disk for said gear having a projecting split hubformed with teeth-registering. With said splines and having a tapered end surface, a clamping ring having a conical inner surface engaging said tapered surface, means exerting axial pressure on said surfaces to contract said hub and secure the same rigidly to said shaft, and a membenconnectingsaid; disk to said gear.

41A. gear assembly comprising a rotatable shaft having a series of axially extending splines formed therein, a gear journalled on said shaft, a driving" disk for said gear having a projecting split? hub formed with teeth registering With said splines and having a tapered end surface, a clamping ringvhaving a conical. inner surface engaging said. tapcredlsurface and. a stop and. nut. on said shaft clamping. said gear, disk. and. ringtogether.

5? A gearassembly comprising. a rotatable shaft having a series of axially extending splines formed. therein, a gear journalled onv saidshaft, a. driving: disk for. said. gear having, a. projecting splithub formed. with teeth. registerin with said splines and having a tapered end. surface, a

clamping. ring. having a. conical inner surface engaging; said. tapered surface, a stop. and. nut. on said shaft clamping said gear, disk and. ring to.-

gethenarad'icallslot insaid disk, andia pincarried by said. shaft entering, said slot to secure. said gear in driving. relationship.

6. A gear assembly comprising. arotatable shaft having a. series.- of; axially extending splines formed. therein, a gear journalled on said shaft over said splines, a driving disk for said gear having a projecting, sp-lithub formed With'teethregistering, with saidsplines and having. a tapered end surface, a clamping rin having a conical. inner surface engagingsaidLtapered. surface, stop-means onsaid shaft, a nut.- threaded on saidshaft over said splines to clamp said gear, disk and ring against said stop means for contracting said hub and rigidly securingv thev same. to said shaft, and

a member connecting. said disk to drive said gear.

, HENRY J. KENT.

REFERENCES CITED UNITED STATES PATENTS Date Number N'ame;

101,824 Clark Apr. 12,:1870 173,126 Little Feb. 8,, 1876 1,407,568 Page 1 Feb.,21-, 1-922 1,511,910. Royce Oct. 14. 1924 2,270,583

Forton Jan. 20, 1942 

